Fischer-Tropsch processes invariably use water/steam as the cooling medium for this exothermic process. Thus, boiling water is pumped through cooling tubes in the reactor. As the reaction proceeds and heat is generated, it is absorbed by the water converting it to steam and thereby using the, latent heat of vaporization to control reactor temperatures. Fischer-Tropsch reactions, particularly on a commercial scale, require many, many cooling tubes, whether for fixed bed or slurry operations, for maintaining proper temperatures. Thus, the risk of a tube failure or weld leak is compounded significantly. In the event of a tube leak, the contents of the reactor are normally at a higher pressure than a boiling water/steam coolant and reactor contents will leak into the cooling system resulting in severe contamination and ultimately shut down of the process. While steam/water cannot be pressurized to greater pressures than the reaction process, because the temperature would be too high, even if it could, a leak of steam into the process will tend to deactivate the Fischer-Tropsch catalyst. Consequently, a medium that is inert to the process is required.